Epidemiological evaluation of ethyl glucuronide levels in different keratinic matrices

Introduction and Aims. Ethylglucuronide (EtG) is an important direct metabolite of ethanol. Recently, an international consensus fixed a hair cut-off value of 30 pg/mg to discriminate social and heavy drinkers. We analyzed more than 2000 samples (head, pubic, chest and axillary hair) to epidemiologically evaluate the distribution of EtG, not in order to differentiate groups according to EtG concentration data or alcohol consumption, but rather to show discrepancies due to: i) sampling region, ii) cut-off applied, iii) geographical origin, and iv) age and gender. The results obtained focus on statistical analysis, on the assumption that large population data-sets will level off the statistical contribution of the average alcohol consumption. Methods. Samples were collected by two medical commissions (located in Northern Italy) which examine a broad range of individuals, namely owners of driving licences, requested to undertake medical examination in order to obtain the renewal of their suspended or expired licences. EtG in hair was determined by HPLC-MS/MS operating in SRM mode. Results. Statistical differences were observed in EtG concentrations recorded in head (N=1709), axillary (N=268) and pubic hair (N=61) samples. Chest hair (N=33) showed EtG distribution similar to head hair, although the large discrepancy between the dimension of examined populations presently prevents definitive conclusions. The percentage of hair samples classified as positive ranged from 15.9% if a 30 pg/mg cut-off value was applied (EtG ranging from 30 to 1189 pg/mg, mean=104.2, SD=121.1), to 10.5% if a more conservative 50 pg/mg value was preferred (mean=138.8, SD=137.6). Axillary hair samples above 30 pg/mg were 3.0% of the total samples (EtG ranging from 30 to 185 pg/mg, mean=95.3, SD=57.0), while positive pubic and chest hair samples were respectively 60.7% and 15.2% (pubic: EtG ranging from 30 to 30562 pg/mg, mean=1776, SD=5302; chest: EtG ranging from 30 to 174 pg/mg, mean=68.5, SD=51.0). Further statistical elaborations on all samples with measurable EtG concentration (>10 pg/mg; N=600) showed variability based on geographical origin, age and gender. Conclusions. EtG is becoming a common and accurate biomarker to identify social and heavy drinkers. Nevertheless, large variability of EtG concentrations due to sampling region and biological differences suggest to responsibly consider a general surveillance policy for the subjects evaluation before any sanction is assigned.